A variety of electronic devices such as portable computers, portable phones, personal digital assistants, and other portable and non-portable electronic devices may utilize one or more DC to DC converters. DC to DC converters generally convert an input DC voltage to a regulated output DC voltage. A DC to DC converter may be utilized to serve a variety of loads within an electronic device. The load served by the DC to DC converter may vary from a relatively light load to a relatively heavy load. The distinction between a light and heavy load may vary based on a particular application, system, and/or user requirement.
Different types of DC to DC converters may be more suitable for serving light or heavy loads. A linear mode voltage regulator may be one type of DC to DC converter that is more suitable to providing power to light loads. The linear mode voltage regulator may monitor changes in output DC voltage and provide a control signal to a transistor to hold the output voltage at the desired value. One type of a linear mode voltage regulator may be a low drop output voltage regulator (LDO) that can provide power to a relatively light load with relatively little voltage drop and with a low noise output. Another type of DC to DC converter may be a switch mode DC to DC converter that holds the output voltage at a desired value by turning at least one transistor of the DC to DC converter ON and OFF. Such a switching type of DC to DC converter may provide a regulated output voltage at a relatively high efficiency when serving a heavy load.
A conventional method of serving one load that may be either a light or heavy load under differing conditions is to provide one DC to DC converter, e.g., an LDO, for serving the light loads, and to provide another separate DC to DC converter, e.g., a switching mode DC to DC converter, for serving the heavy loads and to switch over between each DC to DC converter under certain circumstances. Such a conventional method requires two DC to DC converters and additional components and pins to facilitate switching between each adding cost and complexity.
Accordingly, there is a need for a controller for one DC to DC converter to have both linear mode and switch mode capabilities.